Refrigeration system



July 23, 1935. M. R. MOORE REFRIGERATION SYSTEM Filed July 24, 19:54:`

4 Sheets-Sheet 1 July 23, 1935.

. M. R. MOORE 2,009,373 REFRIGERATION SYSTEM Filed July 24, 1954 4 sheets-sheet 2 lil 6O 65 M Z# A 2 l 4 Humm.. g r ./'1/ -r l' ,E-g 1 l lf/d 23 1 |\l\\""" 'I i gmc/WM MRMDUFE July 23, 1935. M. R. MOORE RERIGERATION SYSTEM Filed July 24, 1934 4 Sheets-Sheet 3 July 23, 1935. M. R. MOORE 2,009,373

REFRIGERATIQN SYSTEM Filed July 24, 1934 4 sheeis-sheet 4 'far I v Patented July 2351935.

aoo'a'svs'Y nEFmGEnA'rroN SYSTEM Marlon B. Moore, Atlanta; Ga., assignor of onethird to C. L. Emerson, Fulton County, Ga., and one-third to Bryan Blackburn, Coweta County, Ga.

v Application July 24, 1934, Serial No. '136,798

tem`of that type in which the liquefactionof the denser without the aid of a compressor by a heat abstracting medium, such as ice, or the evaporatnig element of a mechanical refrigerationsystem.

It isessential to'asystem of the type described for means to be provided for conducting the lique- 'fled refrigerant from th condenser back to the evaporator or at least as' far as the expansion valve which admits the refrigerant to the evaporator. 1 Otherwise the system becomes static since pressm'e developed in the evaporator by the vola.'- tilization of the refrigerant acts with substantially equal pressure at both ends of. the evaporator coil. A One of the objects of the present invention is to provide a pump for the liquid refrigerant which operates responsive to pressure differential be-` tween the high and low sides of the refrigeration4 circuit. v

`Another object of the invention is the provision of a pump having pistons of different area whereby the pressure differential between the high and low sides of the system is magnified. Since by virtue vof its position -between the high and low limbs of the refrigeration circuit the motor element of the pump mu'st be actuated by a fluid whichfhas already done the majorportion 'of its expanding' in. the evaporator,` provision is made forrnaintaining the motor cylinder in. communication-with the low sideY of the refrigeration system .during substantiallythe entire working stroke of the piston whereby Ithe. latterl is impelled throughout its stroke by pressure derived in the mainl from expansion outside the cylinder.

Consequently, another object of the invention is the provision of valve control means for the motor cylinder of A'the pump designed to hold the inlet valve open and the exhaust valve s hut during the working stroke of the motor. cylinder and to snap the inlet valve suddenly into closed position, and the exhaust-valve into open position, when .the piston approaches the lower limit of its range of travel, the operation being reversed when the piston reaches its upper limit. v

A'further. object ofthe invention is the provision of a, pump in which both the motor an pumping pistons are spring returned. l A further object of the invention is to provide means for cooling the pumping cylinder so that the liquefied refrigerant will not fiash Inma stroke of the pumpingpiston.

of the invention will appear as gas in the pumping cylinderupon the suction Other l objects y y 1s claims.- .(cl. s2-125) This invention'relates to a refrigeration systhe following description of a preferred and practical embodiment thereof proceeds.

YIn the drawings which accompany and form a part of the following specification and throughout the several figures of which the sanie charac- 5 ters of reference have been employed to designate identical parts: f

Figure 1 is a vertical section through the pump taken somewhat irregularly along the line I I Figure 2 is a horizontal section taken along the line 2 2 of Figure'l. The arrows along the section lines indicate the direction of aspect; f

Figure 3 is a vertical elevation viewedfrom the right in Figure 1; 15

Figure 4 is a section through the 'piston taken long the line 4 1 of Figure 1;

Figure 5 is a side elevation of the snap action which controls the inlet valve in the opposite position to that shown in Figure 3;

Figure 6 is a detail in end elevation showing the cam which is xed to the piston operated sleeve;

Figure 7 is an end view of the said sleeve with the inlet and exhaust cams secured thereto, show- 25 ing their relative positions;

Figure 8 is a vertical section illustrating the refrigeration system;

and first adverting to the system shown in Figure 8, the numeral 1 represents the pump which is intercalated between the high side 2 and the low side 3. The pump is actuated by gaseous 40 refrigerant under pressure passing from the evapv orator 4 to the condenser 5. The pump inducts liquid refrigerant by wayv of the conduit 6 from the lower part of the condenser and forces it into a receiver 1 and into a conduit 8 upto the 45 expansion valve 9 where the liquid refrigerant is admitted to the evaporator coil according to the refrigerating needs determined by a thermostat l0 in the refrigerated chamber II which thermostat controls the functioning of the expan- 5o y sion valve.

Turning now to Fig. 1, the pump I comprises a casing forming a cylinder l2 for the motor piston secured to a 'second casing forming a pumping cylinder I3, the pumping cylinder bel5 ing co-axial with the motor cylinder. within -the respective cylinders are the motor piston I4 verted cup-like collar I1 suitably secured. vThe spring I6 normally biases both pistonsV to the upper end of their stroke.

The motor cylinder as shown is of the T-head F type being provided with intake and exhaust valve chambers I8 and I9,respectively, communication of the motor cylinder with said chambers ybeing controlled by the respective inlet and exhaust valves 20 and 2I. Said valves are operated by cams 22 and 23 fixed upon a shaft 24 bestshown in Figure 2, in such relation that when the inlet valve is open the exhaust valve is closed and vice versa. As will be shown, the said valves do not operate in completev synchronism with the motor piston I4 since it is essential that the motor piston shall have traversed its stroke in one or the other directionslbefore one valve opens and the other closes, and in the interest of emciency, it is necessary that the inlet valve shall be fully open and the exhaust valve fully closed during the entire duration of the working stroke of the motor piston. Since the pressure of the gaseous refrigerant whichV operates the motor piston I4 is at the best ff, slight, conservation means are employed to-prevent leakage, said means including a sylphon 25 bridging the joint between the inlet valve stem A26 and the guide 21 within which it reciprocates. The upper end -of said sylphon is welded to the valve stem at-,28 while the lower end is expanded into a cup 29 which is pressed in iluidtight manner into the bottom of a recess 30 formed at the upper end of the valve guide 21.

Such expedient is not necessary with regard to the exhaust valve 2I since the joint between/the exhaust valve stem 3| and the guide 32 is outside of the cylinder chamber and not in a position where leakage of gas would be of any consequence. n

The casting which forms the pump cylinder I3 is formed as a plate 33 constituting a head for the lower end of. the motor cylinder, said plate being secured in huid-tight manner to the un der'side of the casting I2, a gasket 34 preferably n intervening. This gasket is preferably of heat insulating material and it is also preferred to interpose heat-breaking strips 13 and 14 between those parts of the cylinder casting I3 which would otherwise come into contact with or in close proximity to the cylinder' I. Thus heat lost from the cylinder I to the cold cylinder I3 is minimized, avoiding the. probabilitylof any refrigerant in the cylinder I condensing into a liquid.

The fluid-tight connection of the plate 33 with the casting which forms the cylinder I2 prevents any refrigerant in gaseous state which may leak past the rings of the piston I4 into the chamber beneath the piston from escaping linto the chamber 31 and going out with the brine which ows through said chamber. yThe wall of the cylinder I2 is perforated at 1I permitting said gasesas may get by -the piston rings to enter the valve chamber and to pass through a port 12 into the exhaust valve chamber I9 to be carried away through the high side of the refrigerationsystem tothe condenser.

' The casting forming, the cylinder I2 is sup- `duction valves for the pump cylinder I3.

ported upon a hollow base 35 closed at its bottom by a plate 36 and defining a chamber 31 into which the lower portion of the pump cylinder protrudes. Check va.lves 38| and 39 are in communication with the pump cylinder, one opening toward and the other away from said cylinder as shown, and constituting the eduction and in- The valve 38 leads to the receiver 1 while the valve 39 communicates with the conduit 6 which comes from the lower part of the condenser. Cover plates 40 and 4I occlude openings in opposite sides of the cylinder casting and give access to the operating mechanism which actuates the inlet and exhaust valves 20 and 2|.

Now referring to the means which retards the actuation of the valves until the motor piston has approached the end of its stroke in either direction, Fig. 2 indicates a sleeve 42 surrounding the shaft 24. Said sleeve oscillates synchronously with the reciprocation of the piston I4 by means of a crank 43 keyed to said sleeve and connected to the piston by a connecting rod 44, the latter having its upper end pivoted on a pin 45 mounted in the piston body at its lower end and pivoted to the crank 43. When the piston descends, the crank 43 rocks downwardly and when the piston I4 ascends the crank reverses the direction of its motion.

Fixed to the end of the sleeve 42 adjacent the inlet cam 22 is an oscillating actuator 46, see Fig. 6.v Said actuator has the form of aiV crank, having' -an outwardly projecting lug 41. ASaid lug extends through an arcuate slot 48 formed in the inlet cam 22, the length of the slot being such that the lug does not directly disturb the repose o f said cam in the course of oscillation of said actuator. The lug 41 extends through an arcuate slot 49A in a snap hammer 50 freely mounted upon the end of lthe shaft 24 and retained against endwise displacement by any suitable means such as the split ring 5I which seats in a groove in said shaft. 'I'he snap hammer is tion of the snap hammer the spring is stretched as it crosses dead center and throws the hammer with considerable force to one or the other side of dead center according to the direction of movement of said snap hammer.

The concerted action of the parts is thus: Assuming the inlet cam 22 to be holding the inlet valve 20 open'as in Figure 3, the piston starts to descend, oscillating the shaft 24 so as to bring the actuator downward. The lug 41 on the actuator comes into contact with the right hand end of the short slot 49 in the snap hammer. It pulls the snap hammer down until the pin 53 which anchors the spring 52 to the snap hammer is at dead center. During all this time the cam 22 has not been moved in view of the amplitude of the slot 48. The lug 41 draws the snap hammer 50 beyond dead center whereupon thespring 52 freely contracts throwing the snap hammer quickly upwardly bringing the shoulder 54 into impactive contact with the pin 55 on the inlet cam throwing said cam over to the position shown in Figure 5 in which the nose 5S of said cam is out of contact with the valve stem 26, permitting the valve to close. The exhaust cam 23 being fixed to the same shaft as the inlet cam 22 has oscillated through a similar arc and opened the exhaust valve. Instantly, the energy of the spring i6 overcomes the pressure of the gaseous refrigerant escaping through the exhaust valve and the motor piston rises to the top of its stroke.

' wise drawing the lsnap hammer downwardly in the opposite direction against the tension of the I spring 52 until deadcenter has been passed whereupon the ysnap hammer over-runs the lug -41 which brings its shoulder 51 into impactive contact with the'pin 58 on the opposite side of the inlet cam, throwing said cam back into the position in which the nose 56 engages the valve stem 26 holding the inlet valve open. By the same movement the exhaust valve is closed.

It is to be noted that ,the valves are arranged in such a manner that on the downward stroke the gas pressure exerts itself on top of the exhaust-valve, helping to keep it seated. On the upward stroke the high pressure gas is exerted on top of the intake valve to aid in seating it. This lessens the duty required of the valve springs.

Since the pump piston is unitary with the motor piston it performs its cycle simultaneously.

. When it ascends, it draws liquid refrigerant through the check valve 39 from the condenser. When it descends the check valve 39 closes against back pressure of the refrigerant, and the check valve 38 opens, the liquefied refrigerant being forced outwardly through the check valve 38 and into the receiver.

fin the cylinder and raises the it will vaporlze.

As the liquefied refrigerant is near its critical state it is obvious that unless provision be made to prevent it, the liquid will :dash into a 'gas ,wit-hin the pump cylinder I3 when the pumping piston rises.. This is avoided by admitting cold brine to the chamber 31 which brine cools the liquid refrigerant'down to such a temperature that it will not volatilize upon thel reduction of pressure incident to the lifting of the pumping piston I5.

The brine is conducted from the lower part of the condenser tank 59 by a pipe 6|) opening into lthe chamber v.31 at 6I. 'I'he chamber discharges through the port 62 by way of a pipe 63 shown in Fig. 8. The head of liquid brine inthe condenser tank 59 is regulated by having the pipe 63 swivelled so that its discharge end 84 can be moved upwardly or downwardly as indicated by the dotted arc-65. 'I'he brine level is preferably -kept at such point that the chamber 31 will always be substantially full.

The liquid refrigerant in the pump cylinder is also keptl from any tendency to flash into a gas when the pressure is relieved on the suction stroke of the pump piston, by the relative level of the bottom of the condenser coil to the upward limit o'f the stroke of thepump piston. 'I'he bottom limb of the coil 5 which may be considered atv the-same level as the liquefied refrigerant, isy preferably several inches higher than the upper end of the pump cylinder when the pump piston is at the top of its stroke. This head of liquid exerts-a pressure upon the liquid point at which Figure y shows an alternative arrangement for connecting the condenser to thebrine space within the base, which is employed when the brine is not continuously replenished as in the case of ice, but recurrently circulated as when a mechanical refrigerating unit is employed to cool the condenser or when eutetic brine is employed. In order to produce a closed path for the thermosiphonic circulation of brine, the inflow pipe 60 enters the base of the pump unit near the bottom, while the pipe 63 is no longer swivelled, but connected to the condenser chamber near the top.

'I'he pump l is preferably seated in a pan 6i which collects melting frost that may from time Ato time run down vfrom the surface of the pump. The pan drains by way of a pipe 61 and in order that the inlet of the pipe 61 shall not become frozen causing overflow of the pan 66, the brine from the pipe 63 preferably overflows into the said pan.

The condenser is preferably of the cross fin construction comprising horizontal ranks and banks of tubes, the tubes in common passing through the plates or fins 68. The fins are extended downwardly to the bottom of the liquid brine so as to take full advantage of the cooling eect of the brine. Theltank 59 as shown is designed to be packed with a mixture of ice and salt.

- 'I'he receiver 1 is formed with a pressure equalpanding spring 10. When a sudden increase in the refrigeratin'g demands occurs and the receiver 1 tends to empty faster than it is supplied by the pump, the sylphon expands. When the opposite conditions prevail, that is to say, when the thermostat I0 rst closes the expansion valve 9, and the pump supplies liquid to the receiver faster than vit is fed to the expansion valve, the sylphoncontracts. In the ordinary operation of the system however, the work done by the pump is in direct proportion to the demands of the evaporator and consequently, the pressure in the receiver will be substantially uniform.

In view of the high eiliciency in the functioning of this pumping unit due in the first place.

to the admission of the actuating fluid during the entire working stroke, and also owing lto thedifferential ratio' in the areas of the motor and pumping pistons, an adequate working pressure is developed enabling the evaporator unit to be located within any reasonable distance remote from the condenser and pumping mechanism. Thus it' is quite feasible to have the condenser and pumping unit occupy the space now devoted to one of the ice bunkers at the ends of a freight car. The other ice bunker may be done away with increasing the capacity of the car and the evaporator may be situated in any desirable location as for example, along the roof pump and condenser. This is only one of the exemplary utilizations of the present invention.

What I claim is:

1. Refrigeration system including an evaporatoi and a condenser with high .and low side connections therebetween, a receiver in said low side connection, an expansion valves thermostatically responsive to refrigerating demands in said high side connection adjacent said evaporator, a pump for maintaining a head of liquid refrigerant in said low side up to said expansion valve having a motor element actuated by gaseous pressure in the high side, said expansion valve normally controlling the actuation of said pump according to refrigerating demands, andcompensating means in said-receiver for substantially equalizing the pressure of liquid in said receiver atv the moment of opening and closing o f said expansion valve.

2. Refrigeration system comprising a closed conduit including a circulation path for a refrigerant passing through a cycle involving a change of state, a pump including a otor. cyliny der and pumping cylinder with synchronously moving pistons in said cylinders, the pumping piston actuating fluid in the liquid limb of said circulation path, the motor pistonbeing actuated by iuid pressure generated by the expansion of a gas in the gas limb of said circulation path, inlet and exhaust valve serving said motor cylinder,`and voperating mechanism for said valves deternrining a simultaneous lag in the closing of said inlet valve and the opening of said exhaust valve until the piston has reached the downward limit of its stroke, whereby the motor piston will be exposed to the pressure in said gas limb during its entire working stroke.

3. Refrigeration system conduit including a circulation path for a recomprising a closed frigerant"passing through a cycle involving. a

change of state, a pump including a motor cylinder and a pumping cylinder with unitarily related pistons operating therein, the pumping piston actuating fluid inthe liquid limb of said circulation path, the motor piston being actuated by `fluid pressure generated bythe expansion of a gas in the gas limb of said circulation path, inlet and exhaust valves serving said motor cylinder, and operating neohanism for said valves determining a simultaneous lag in the closing of lsaid inlet valves and the opening of said exhaust valve until thepiston has reached the downward limit of its stroke, whereby the piston will be exposed to the gas pressure during its entirel working stroke, said valve operating mechanism comprising a shaft, an inlet and an exhaust cam on said shaft engageable with the stems of the corre spun-ding valves, said cams being so displaced asa to cause the simultaneous closing of one valye and the opening of the other, means oscillated by Asaid piston, normally moving independently of said shaft, but operably engaged therewith at the extremities of the piston stroke for oscillatingsaid shaft.

4. Refrigeration system comprising a closed conduit including a circulation path for'a refrigerant passing through acycle involvingv a change of state, a pump including a motor cylinder and a pumping cylinder with unitarily related pistons operating therein, the pumping piston actuating fiuid in the liquid limb of said circulation path, the motor piston being'actuated by fluid pressure generated by the expansion of a gas in the gasv limb of said circulation path, inlet and exhaust valves serving said cylinder,

and operatingmechanism for said valves determining a simultaneous lag in the closing of said inlet valves and the opening of said exhaust valve until the piston has reached the downward limit of its stroke, whereby the piston will be exposed. to the gas .pressure during its enti-re working stroke, said valve operating mechanism comprising a shaft, an inlet and an exhaustV cam on said shaft engageable with' the stems of the corresponding valves and displaced so as to cause the simultaneous opening of one valve and closing of the other, Aa snap hammer having aneutral dead center position and active positions on opposite n sides of dead centerin each of which positions it is engageable with one of said cams for oscillating said cams and said shaft, and means oscillated by said piston, independent of said shaft engageable with said snap hammer adjacenthe extremities of the piston stroke for oscillating said 'snap hammer. v

5. Refrigeration system including an evaporalpump cylinder with haust valves serving said motor cylinder, and

means delaying the closing of the inlet valve and opening of the exhaust valve until the piston has substantially reached thel downward limit of its stroke, whereby the piston will be exposed to the extraneously generated pressure during its tor and a condenserwith high and low side conf nections therebetween, a receiver in said low'side connection, an expansion valve in said high side connection adjacent said evaporator, thermostati ically responsive to refrigerating demands, a, pump for maintaining a head of liquid refrigerant i-n said low side up to the expansion valve, said pump having a motor cylinder and av pump cylinder, with synchronously moving pistons therebetween, the motor cylinder being intercalated in the high side connection and the motor piston being actuated by gaseous pressure generated by expansion of the gaseous refrigerant, for the most part externally of the motor cylinder, inlet and exhaust valve serving said motor cylinder, means delaying the closing of the 'inlet valve and the opening of the exhaust valvel until the piston has substantiallylreached the downward limit of its stroke, whereby the piston will be exposed to the extraneously generated pressure during its entire working stroke, said expansion valve normally governing the actuation of said pump according yto refrigerating demands through its control of the refrigerant admitted. to saidV evaporator, and compensating means in said receiver for substantially equalizing the pressure of liquid in said receiver at the moment of opening and closing said expansion valve.

8. Refrigeration system including an evaporator and a condenser with high and low side connections therebetween, an expansion valve in said highside connection adjacent said evaporator, a pump for maintaining a head of liquid refrigerant in said low side valve, said pumpl having a motor cylinder and synchronously moving pistons therein, said cylinders being intercalated respectively in said high and low side connections, the motor piston being actuated by gaseous pressure `generated by expansion of the gaseous refrigerant, for the most part externally of said motor cylinder, inlet and exhaust valves serving said motor'cylinder.' means delaying the closing of the inlet valve and ythe opening of the exhaust valve until the piston has ysubstantially reached the downwardlimit of its stroke whereby the motor piston will be exposed to the extraneously generated pressure'during its entire working stroke, and means for preventing the liquid refrigerant in the pump cylinder flashing into a gas on the suction stroke of the pump piston.

9. Refrigeration system including an evapora- 'up to said expansion. f

tor and a condenser with high and low side connections therebetween, an` expansion valve in said high side connection adjacent said evaporator, a pump for maintaining a head of liquid refrigerant in said low side up to said expansion valve, said pump having a motor cylinder and pump cylinder with synchronously moving pistons therein, vsaid cylinders being intercalated respectively in said high and low side connections, the motor piston being actuated by gaseous pressure generated by expansion .of the gaseous refrigerant, for the most part externally of said motor/cylinder, inlet and exhaust valves serving said motor cylinder, means delaying the closing of the inlet valve and the opening of the exhaust valve until the piston has substantially reached the downward limit of its stroke whereby the motor piston will be exposed to the extraneously generated pressure during its entire working stroke, and means for cooling said pump cylinder to prevent the liquid refrigerant in the pump cylinder ashing into a gas on the suction stroke of the pump piston. .Y

10. Refrigeration system including an evaporator and a condenser with' highand low side Vconnections therebetween, an expansion valve in said high sideconnection adjacent said evaporator, a pump for maintaining a head of liquid refrigerant in said low side up to said expansion valve, said pump having a motor cylinder and pump cylinder with unitarily related pistons therein, said cylinders being intercalated respectively in said high and low side connection, 4the motor piston being actuated by gaseous pressure generated by expansion of the gaseous refrigerant, for the most part taking place externally of said motor cylinder, inlet and exhaust valves serving said motor cylinder, means for delaying the closing of said inlet valve and the opening of the exhaust valve until the piston has substantially reached the downward limit of its stroke whereby the piston will be exposed to the extraneously generated pressure-during its entire working stroke, a hollow base supporting said cylinders and into which the pump cylinder projects, and means for circulat-` ing cooling medium through said base about said pump cylinder toprevent the liquid refrigerant in the pump cylinder flashing into a gas on the suction stroke .of the pump piston.

11. Refrigeration system comprising a closed conduit including a circulation path for a refrigerant passing through a cycle involving a change of state, a pump including motor and pumping cylinders A,with synchronously moving pistons in said cylinders, a hollow base supporting said cylinders and into which the pumping cylinder projects, the pumping piston actuating fluid in the liquid limb of said circulation path, the motor piston being actuated by fluid pressure generated by the expansion of refrigerant in a gas limb of said circulation path, inlet and exhaust valves serving rsaid motor cylinder, valve operating mechanism engageable with the stems i of said valves determining a simultaneous delay in the closing of said inlet valve and opening'of said exhaust` valve until the piston has reached the downward limit -of its stroke, whereby the piston will be exposed to the extranequfsly generated pressure during its entire working stroke, said motor cylinder being provided with guides for said valve stems, means for sealing the joint between the inlet valve stem and guide against leakage from said cylinder, means for sealing the lower part of the motor cylinder against leakage into the chamber of said base, means providing a closed lconduit for discharging such as may leak past the joint between the motor piston and cylinder to the` exhaust passage beyond said exhaust valve, and means for admitting the cooling uid to said hollow base for cooling the uid within said pumping cylinder. v

12. Refrigeration system including an evaporator and a condenser with high and low side connections therebetween,v an expansion valve be-l tween said high side connection adjacent said evaporator, a pump for maintaining a head of respectively in said high and low side connections, the motor piston being actuated by gaseous pressure generated by the expansion of the gaseous refrigerant, for the most part taking place externally of -said motor cylinder, inlet and exhaust valves serving saidA motor cylinder, means delaying the closing of the inlet valve and opening of the exhaust `valve until the piston has substantially reached the downward limit of its stroke, whereby the motor piston will be exposed to the extraneously generated pressure during its entire working stroke, said condenser including a coil in a brine tank, means for maintaining a head of brine in said brine tank, means connecting said brine tank with the chamber of said base,

said chamber having a brine discharge ensuring a ow of cooling brine about said pump cylinder` -to prevent the liquid refrigerant in the pump cylinder flashing into a gas on the suction stroke Amotor and pump cylinders intercalatedin said high and low side connections respectively with synchronously moving pistons therein, the motor piston being actuated by gaseous pressure generated by expansion of the gaseous refrigerant, said condenser including a coil in a brine tank, means for maintaining a head of brine in said brine tank, and means for conducting brine from said -brine tank about said pump cylinder to prevent the liquid refrigerant in the pump cylinder flashing into a gas on the suction stroke of the pump piston. g

V15. Refrigeration system including an evaporator and a condenser with high and low side conv nections therebetween, an expansion valve in said high side connection adjacent said evaporator,

a pump for maintaining 'a head of liquid refrigerant in the low side up to said expansion valve, said pump `bridging the high and low side connections between said evaporator and condenser, having motor and pump `zylinders intercalated in said high and low side connections respectively with synchronously moving pistons therein, the motor piston being actuated by gaseous pressure generated by expansion of the gaseous refrigerant, said condenser including a coil in a brine tank, means for maintaining a head of brine in said brine tank, means for conducting brine from said brine tank about .said pump cylinder to prevent the liquid refrigerant in the pump cylinder hashing into a gas on the suction stroke of the pump piston, and means for varying the head of brine in said brine tank.

16. Refrigeration system including an evaporator and a condenser with high and low side connections therebetween, an expansion valve in said high side connectionv adjacent said evaporator, a pump for maintaining a head of liquid refrig-I erant in said low side connection up to said expansion valve, said vpump bridging saidl connections having a motor cylinder intercalated in the high side connection and a pump cylinder in the loW side, with synchronously moving pistons therein, said motor piston being actuated by gaseous pressure generated by expansion of gaseous refrigerant mainly in said evaporator, said condenser including a coil in a brine tank, means for maintaining a head of brine in said brine tank above the level of at least a portion of said pump cylinder, means for conducting brine from said brine tank about said pump cylinder to prevent the liquid-refrigerant in the pump cylinder flashing into a gas on the suction stroke of the pump piston, Aand means for varying the level of the therein, the motor piston being actuated'by gaseous, pressure generated by expansion of the gaseous refrigerant, said condenser includingr a coil in a brine tank, said coil being placed at such elevation that the level of liquid refrigerant in said condenser is above the upper limit of travel of the pump piston to prevent the liquid refrigerant l within said pump cylinder flashing into a gas on the suction stroke of the pump.

18. Refrigeration system including an evaporator and a condenser withl high and low side connections therebetween, an expansion valve in said high side connection adjacent said evaporator, a pump for maintaining a head of liquid refrigerant in said low side connection up to said expansion valve, said pump bridging said connections, having a. motor cylinder intercalated in the high side connection anda pump cylinder in the low side with synchronously moving pistons there- Iin, said motor piston being actuated by gaseous pressure generated by expansion of the gaseous refrigerant mainly in said evaporator, said condenser including a coil in a brine tank, said coil beingJplaced at such height withrespect to said pump cylinder that the level of liquid refrigerant in said condenser is above the upper limit of travel of the pump piston, means for maintaining a head of brine in said brine tank above the level of at least a portion of said pump cylinder, and means for conducting brine from said brine tank about said pump cylinder, the maintenance of a head of liquid refrigerant above the upper limit4 of said pump piston, and the maintenance of a head of brine above the level of at least a portion of the pump cylinder together preventing the liquid refrigerant in the pump cylinder flashing into a gas on the suction stroke of the pump piston.

, MARION R. MOORE. 

